This invention relates in a first aspect to a tubular reactor, and more particularly to such reactor comprising a reactor tube having two open tube ends, inlet means for the substances to be processed, at one of these tube ends, and at least one outlet for the product to be obtained at the other tube end, inset means in the reactor tube being axially displaceable therein, as well as drive means for an axial to-and-fro displacement of the inset means relative to the reactor tube.
In a second aspect, the invention relates to the use of the aforesaid reactor for continuously performing heterogeneous reactions therein. However, the reactor is also suitable for performing heterogeneous reactions the heat exchange of which is to be accelerated.
In a third aspect, the invention relates to a novel process for continuously performing a heterogeneous reaction.
In former times chemical reactions were carried out in apparatus which was specially designed for a specific reaction. In the beginning of this century factors influencing chemical reactions such as the influence of flow, mixing, distribution of sojourn times and the transfer of substances and of heat were more generally investigated. The concept of chemical reaction techniques originated only in the mid-Fifties. The field of reactor development is therefore a relatively young one and, correspondingly, comprises many problems to be solved.
A particular problem, hitherto unsolved in a satisfactory manner in the field of reaction techniques, is the control of heterogeneous reactions. Particularly in those cases in which a re-mixing of reactants and reaction products has a negative influence on the alternate outcome of the process, e.g. on a possible subsequent reaction step, and which require a thorough mixing in order to accelerate the reaction, the selection of a suitable reaction apparatus becomes difficult. Hereinafter, a few known reactor types shall be briefly discussed.
As a first reactor type a vessel equipped with a stirrer is well-known. This apparatus comprises a vessel in the interior of which the stirring elements, e.g., rotating propellers or vane elements are lodged. With the aid of stirrer-equipped vessels, it is possible to attain an excellent degree of mixing. As, however, the starting components as well as the resulting final product are present in the same vessel and are being continuously mixed with each other, a re-mixing thereof is unavoidable, as it is inherent in the technical system.
A further frequently used type of reactor is the tubular reactor which comprises a cylindrical tube into which the starting components are introduced at one end thereof. Due to the continuous flow of additional material into the tube, the starting components are pushed through the tube while reacting with each other during their travel through the tube, while the resulting end products leave the tube at the other end thereof. As the flow of subsequent components pushes those already in the tube ahead of them, remixing is relatively minor. On the other hand, due to the laminar flow of the substances through the tube, mixing of the same is not particularly satisfactory. Moreover, tubes of great length may be required in order to guarantee the necessary sojourn times for completing the reaction.
A combination of a tubular reactor and stirrer-equipped vessel is provided by subdividing the tubular reactor into several chambers, each of which is designed as a stirrer-equipped vessel, and which are arranged as a series of cascades, wherein the components do not remain stationary in the stirrer-equipped chambers during mixing, but flow through the same. However, this combination suffers from several drawbacks. Centrifugal forces generated by the stirrer element cause a sedimentation of particles. Furthermore, the angular velocity of the stirrer element is not the same at all points, but is smallest near the driving shaft of the stirrer so that no uniform mixing can be attained. As a further drawback the component parts of the reactor are difficult to clean.
Further reactors have been described, for instance, in the French patent publication No. 2,321,513, the German patent publication No. 1,125,175, and the U.S. Pat. Nos. 3,716,590 and 4,268,437. These known reactors are badly suited or completely unsuitable for carrying out heterogeneous reactions.